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Exams > 2020 Q26 — SMM Adverse Containment

2020 Q26 — SMM Adverse Containment

⚠️ DRAFT
Q26 — SMM Adverse Containment WE16EK2.1 (3.0)
Given:
Unit 2 has experienced a LOCA.

At T+0:
• Containment Pressure has peaked at 10 psig.
• 2R44A, Containment High Range Monitor is reading 5E05 R/HR.
• 2R44B, Containment High Range Monitor is reading 7E05 R/HR.

At T+3 hours:
• Containment Pressure is currently reading 2.5 psig.
• 2R44A, Containment High Range Monitor is reading 2E04 R/HR.
• 2R44B, Containment High Range Monitor is reading 1E04 R/HR.

Complete the following statements concerning operation of the Subcooling Margin Monitor (SMM):

At T+0 the SMM is operating in _(1)_ Mode, and at T+3 hours the SMM will _(2)_ reset to Normal Mode.
A. NORMAL; automatically
B. ADVERSE; automatically
C. NORMAL; require manual action to
D. ADVERSE; require manual action to
▶ Show Answer & Explanation
✓ D. Correct. Containment conditions are ADVERSE due to R44A & B indications > 1E05 R/HR and Containment pressure > 4 psig. Although Containment pressure conditions have reset, the SMM does not automatically reset due to radiation levels lowering below adverse numbers.
✗ A. Plausible because the candidate may believe that the High Radiation signal for Adverse Containment condition is > 1E06 R/HR (integrated dose number used in procedure) rather that > 1E05 R/HR and they may believe that both high radiation and high containment pressure are required for adverse conditions. They could also believe that containment high-high pressure of 15 psig is required for adverse conditions. The second part is plausible because when containment pressure lowers to < 3 psig, the SMM will reset due to a previous adverse containment signal. Incorrect as both radiation and containment pressure indicate adverse conditions (only one required) and the SMM does not automatically reset due to radiation levels lowering below adverse numbers.
✗ B. The first part is true, containment radiation levels are adverse (> 1E05 R/HR) as well as containment pressure (> 4 psig). The second part is plausible because when containment pressure lowers to < 3 psig, the SMM will reset from a previous adverse containment signal. Incorrect as both radiation and containment pressure indicate adverse conditions (only one required) and the SMM does not automatically reset due to radiation levels lowering below adverse numbers.
✗ C. Plausible because the candidate may believe that the High Radiation signal for Adverse Containment condition is > 1E06 R/HR (integrated dose number used in procedure) rather that > 1E05 R/HR and they may believe that both high radiation and high containment pressure are required for adverse conditions. They could also believe that containment high-high pressure of 15 psig is required for adverse conditions. Incorrect as both radiation and containment pressure indicate adverse conditions (only one required). The second part is correct.
Ref: 2-EOP-CFST-1, Critical Safety Function Status Trees and Bases | LO: N/A | Source: New | Cognitive: Comprehension

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